In video processing and storage applications, digital video data is typically encoded to conform to the requirements of a known standard. One such widely adopted standard is the MPEG2 (Moving Pictures Expert Group) image encoding standard, hereinafter referred to as the "MPEG standard". The MPEG standard is comprised of a system encoding section (ISO/IEC 13818-1, Jun. 10, 1994) and a video encoding section (ISO/IEC 13818-2, Jan. 20, 1995), hereinafter referred to as the "MPEG systems standard" and "MPEG video standard" respectively. Video data encoded to the MPEG standard is in the form of a packetized datastream which typically includes the data content of many program channels (e.g. content corresponding to cable television channels 1-125). In order for a decoder to decode the packetized datastream and to recover the video data content of selected program channels for display, for example, the individual packets that comprise the selected program channels must be identified and assembled.
In order to recover the content of selected program channels, information in a Program Guide is used in identifying and assembling individual data packets that constitute the selected programs. For this purpose Program Guide data is acquired from the program datastream that is input to a video decoder. The Program Guide data is formed into a Master Program Guide (MPG) sufficient to decode the selected programs. Once it is formed, the MPG may be used to decode the selected programs or it may be transmitted along with the data content of the selected programs to another application device. However, in some video transmission systems, it is necessary to acquire and form the MPG from Program Guide data encoded in variable broadcast encoding formats.
Variable broadcast encoding formats are used in wireless terrestrial video broadcast systems to selectively provide enhanced levels of broadcast signal noise immunity. However, a broadcast encoding format that provides enhanced noise immunity also requires increased transmission bandwidth. An example of a system that uses variable broadcast encoding formats is the proprietary Multipoint Microwave Distribution System (MMDS) which uses a "line-of-sight" transmission system. In such a system, an encoding format that provides a broadcast signal with a higher degree of immunity to noise also incurs a higher error correction coding overhead and consequently requires greater transmission bandwidth. Similarly, for a fixed transmission bandwidth, providing a broadcast signal with a higher degree of noise immunity reduces the information throughput that may be attained. Further, the encoding format used may be varied on a temporal or geographical basis to accommodate variations in reception conditions associated with atmospheric or landscape features.
The variation in broadcast modulation and error correction coding format and the associated required transmission bandwidth presents problems to a video receiver both in decoding the variable encoding formats and in acquiring a compatible MPG. These problems are addressed by a system according to the present invention.